El Niño Is Back and Could Be the Strongest Ever Recorded

What the BOM Just Told Us

The Bureau of Meteorology made it official this week: El Niño is here. According to ABC, the declaration is based on conditions in the atmosphere and oceans across the tropical Pacific, where sea surface temperatures in the Niño3.4 region have now exceeded the El Niño threshold of 0.8 degrees Celsius above normal for the first time since the last event wrapped up in early 2024.

But it is the Southern Oscillation Index that is really setting off alarm bells. The 30-day SOI has crashed to -23.3, which is more than three times beyond the El Niño threshold of -7. To put that in plain language: the pressure pattern across the tropical Pacific has shifted dramatically, and Australia is sitting in the wrong part of it. Other confirming signals include weaker trade winds, changes in tropical cloud cover, and a mass of very warm water building just below the ocean surface.

The Record That Nobody Wanted

Here is where this stops being a weather story and starts being something more alarming. The BOM's own seasonal model, ACCESS-S, is forecasting a peak warming in the Niño3.4 region of more than 3 degrees Celsius above normal. The previous record high for a post-1900 El Niño event was 2.65 degrees Celsius, recorded in November 1902. ABC reports that this year's rate of warming in that region is already the fastest since 1943.

Since El Niño events typically peak between November and January, an event that has already kicked off in June has roughly six months left to intensify. Six months. The BOM's modelling indicates temperatures in the equatorial Pacific will continue rising rapidly through that entire window. The vast majority of forecasting models agree on this trajectory, which in climate science terms is about as close to a consensus as you get.

The one piece of genuinely good news buried in all of this: ABC notes that there is only a weak relationship between the raw strength of a Pacific warming event and how badly it hammers Australian conditions on the ground. A record event does not automatically mean a record drought. That caveat matters, but it is not exactly the kind of thing you print on a bumper sticker.

What This Actually Means for Australia

Let's be clear about what El Niño typically brings to this country, because the list is not short. According to ABC's reporting, Australians can expect warmer daytime temperatures across southern Australia through winter, spring and summer, cooler nights in winter with increased frost risk, a shorter and leaner snow season, and a longer and harsher fire season driven by drought and a rise in extreme temperature days.

For the tropics, the picture is also grim: a delayed monsoon and fewer tropical cyclones, particularly for Queensland. The BOM's three-month outlook already favours below-median rainfall for much of southern and eastern Australia. Every El Niño event plays out differently, so forecasters won't pretend these outcomes are guaranteed, but the trends drawn from previous events are not encouraging.

The fire season angle is worth sitting with for a moment. Australia has not fully shaken the psychological weight of the 2019-2020 Black Summer fires, which burned through nearly 19 million hectares and killed an estimated three billion animals. El Niño was not solely responsible for that catastrophe, but it was a major contributor. The prospect of a stronger-than-ever event is not an abstraction.

The Weird Part: It's Raining Right Now

Yes, there is a strange contradiction sitting at the centre of this story, and ABC addresses it directly. Even as El Niño is officially declared, a major north-west cloud band has been dumping rain across the southern two-thirds of Australia this week, part of multiple significant rainfall events since early May. So how do both things exist at once?

The answer is that El Niño is an observation about the state of the tropical Pacific Ocean and atmosphere, not a forecast for what is happening in your backyard today. Australia is surrounded by three oceans, and right now the Indian Ocean and Southern Ocean are both pushing the weather in the opposite direction from what El Niño would produce. Local water temperatures are also playing a role. The current wet spell is real. But the BOM is telling us not to get comfortable, because those other oceanic influences are not going to hold the line forever.

Seven Years Without a Break

There is a detail buried at the bottom of the ABC report that deserves more attention than it will probably get. This year is now on track to be the seventh consecutive year in which the Pacific is in either El Niño or La Niña territory. Historically, roughly half of all years are neutral, a condition called a neutral Pacific. Seven consecutive non-neutral years has not happened since the stretch between 1969 and 1976.

What that means, practically speaking, is that the global climate system has been lurching between extremes without pause for the better part of a decade. There is no obvious smoking gun explanation in the BOM data alone, but climate scientists have long theorised that a warming planet could produce more frequent and more intense oscillations between these states. Seven years in a row is not a proof of that theory. It is, however, a data point that should be making people very uncomfortable.